1. Field of the Invention
The present invention relates to an audio signal processing device which mixes audio signals inputted from a plurality of input channels in a mixing bus and outputs an audio signal after the mixing via an output channel corresponding to the mixing bus.
2. Description of the Related Art
An audio signal processing device with a mixing function such as a digital mixer or the like has been known conventionally. For example, a digital mixer with a mixing function having a signal processing configuration as illustrated in FIG. 9 is disclosed in the following Document 1. Further, the configurations of an input channel and an output channel of the configuration illustrated in FIG. 9 are described in more detail in FIG. 10.
Document 1: “DIGITAL PRODUCTION CONSOLE DM2000 Version 2 Owner's manual”, Yamaha Corporation, 2004
More specifically, the digital mixer described in Document 1 includes an input patch 201, input channels 202, mixing buses 203, direct-outs 204, output channels 205, matrix buses 206, and an output patch 207 in a DSP (digital signal processor) being a processor performing audio signal processing.
Among them, the input patch 201 patches one of input ports prepared to correspond to not-illustrated input terminals for inputting audio signals to each of a plurality of input channels 202 respectively, and supplies each of the input channels with an audio signal which is inputted to the input port patched thereto.
Further, each of the input channels 202 includes, as illustrated in FIG. 10, a phase inversion module 211, a noise gate 212, an equalizer 213, a compressor 214, a delay 215, an ON/OFF control module 216 and a level adjustment module 217.
The signal processing modules from the phase inversion module 211 to the level adjustment module 217 perform various kinds of signal processing for adjusting the characteristics of signal such as the amplitude, frequency and the like on the audio signal supplied from the input port. Then, the audio signal after the signal processing is outputted to arbitrary one or more buses of the plurality of buses constituting the mixing buses 203.
Then, audio signals are similarly inputted from a plurality of input channels 202 to the mixing buses 203, and the audio signals inputted from the plurality of input channels 202 are mixed in each bus of the mixing buses 203 and outputted to the output channel 205 corresponding thereto.
This output channel 205 includes, as illustrated in FIG. 10, an attenuator 221, a parametric equalizer 222, a compressor 223, an ON/OFF control module 224, a level adjustment module 225, a delay 226, and a graphic equalizer 227.
The signal processing modules from the attenuator 221 to the graphic equalizer 227 perform various kinds of signal processing for adjusting the characteristics of signal such as the amplitude, frequency and the like on the audio signal produced by mixing in the mixing bus 203.
Further, the output patch 207 patches each of the output channels 205 to one of output ports prepared to correspond to not-illustrated output terminals, and outputs the audio signals after the signal processing in the output channels 205 to the patched output ports.
Due to the above configuration, the digital mixer can mix audio signals inputted from a plurality of input channels 202 in a mixing buses 203 and output audio signals after the mixing via output channels 205 respectively corresponding to the mixing buses 203.
Incidentally, in such a digital mixer, the output channels 205 are used for outputting audio signals for so-called FOH (front of house) of outputting sound from, for example, speakers provided at a stage, in a hall or the like. In this case, the output channels 205 will perform signal processing for adjusting characteristics of the audio signals after the mixing to those suitable for the use of FOH. Further, also during a live of musical performance or the like, processing parameters are edited as needed to finely adjust the state of the signal processing in some cases.
On the other hand, when recording input signals, it is unfavorable to use such audio signals adjusted for FOH. Further, it is also unfavorable that the audio signals for recording are affected during recording by the fine adjustment for FOH. For this reason, there was a need to output the signals processed in the input channels without undergoing the signal processing in the output channels, for output to a recording device and the like.
As a function for the need, a so-called direct-out function of selecting one of output points A to C illustrated in FIG. 10 by a direct-out signal selecting switch 218 and outputting the audio signal at the selected output point in the input channel 202 to the output patch 207 via the direct-out 204 is provided for each input channel in the digital mixer described in Document 1.
In addition to that, a so-called matrix mixer function of selecting one of output points D and E illustrated in FIG. 10 by an output point selecting switch 228 to input the audio signal at the selected output point in the output channel 205 into the matrix buses 206 for mixing is also provided for each output channel. Then, audio signals produced by mixing in the matrix buses 206 are outputted to the output patch 207.
Then, the aforementioned audio signals outputted from the direct-out 204 and the matrix buses 206 to the output patch 207 can also be respectively patched to output ports prepared to correspond to not-illustrated waveform output terminals, similarly to the audio signals outputted from the output channels 205, and outputted from output terminals corresponding to the ports.